This invention relates to new symmetrical bis(unsymmetrical t-alkyl or t-aralkyl azo) compounds (wherein "t" is tertiary) and to synthesis of organic compounds utilizing these novel compounds as sequential free radical initiators, especially to the preparation of polymers containing attached aliphatic azo groups and to block copolymerization using such azo-containing polymers.
Heretofore most syntheses which required sequential free radical initiation utilized two or more different compounds capable of providing free radicals; the compounds being selected to provide free radicals at different conditions as called for by the reaction. Commonly compounds falling into different chemical classes are used.
Bis azo compounds have been known for sometime. Examples of aliphatic bis phenylazos have been prepared. Preparation of trans-1,2-bis-phenylazocyclohexane ##SPC1##
Is disclosed by A. J. Bellamy et al., J. Chem. Soc., part C, Org. (1966), 1989-1993. Preparation of t-butyl-bis(phenylazo)methane ##EQU1## is disclosed by F. Neugebauer et al., Liebigs Ann. Chem. 706, 107-111 (1967). Other bis azo compounds are likewise disclosed in U.S. Pat. No. 2,554,141, in U.S. Pat. No. 3,244,692 and in C. G. Overberger et al., J. Am. Chem. Soc. 80, 6556 (1958) and 77, 4651 (1955). None of these compounds are closely related to applicants novel bis-azo compounds.